Dr. Rick Kittles Breaks Down DNA

Dr. Rick Kittles Breaks Down DNA

One of the researchers from Dr. Henry Louis Gates'​Finding Your Roots​explains what DNA tells us about our African ancestry and ourselves

by Eugene Holley, Jr., May 22, 2012

Dr. Rick Kittles Breaks Down DNA

Dr. Rick Kittles

Dr. Henry Louis Gates’ fascinating, PBS mini-series Finding Your Roots, traces the ancestries of prominent Americans from Branford Marsalis and Condoleezza Rice, to Samuel L. Jackson and John Legend.  But where the genealogical paper trail ends for many African-Americans, due to the history of slavery, the DNA search begins. One of the DNA experts assisting Professor Gates in the series is Dr. Rick Kittles,  a brilliant, forty five-year old geneticist, who serves as Associate Professor in the Department of Medicine; division of Epidemiology and Biostatistics, at the University of Illinois at Chicago.

Kittles also is the co-founder and Scientific Director of African Ancestry, Inc., a nine year-old, ancestry tracing company with a DNA database comprised of over 25,000 African DNA lineages. EBONY spoke with Dr. Kittles about what DNA is, and how it reveals the hidden past, and complexity of our African-American heritage.

EBONY:  We’ve all heard of DNA, but give us a thumbnail sketch of what it actually is.

Rick Kittles: DNA [deoxyribonucleic acid] is the genetic material – the chemical that’s in every cell of our body, that’s important for coding different physical features and traits. You receive half of your DNA from your mother, and the other half comes from your father. DNA is very instrumental in terms of coding for things that make us human: skin color, hair texture, eye color, and physical features. But it also [shows] susceptibility to cancer, diabetes, and other diseases. DNA is important for tracing ancestry because it’s like a record of the history of you as an individual, within your family, community, and within a particular region in the world. We can use that information to trace where a person’s ancestry came from.

We can go all the way back to when humanity started in Africa over 150,000 years ago, or we can look at a more recent window, like for instance, right before the slave trade. Those changes in the DNA are different than the older changes that occurred 150,000 years ago.

EBONY: We know what DNA tells us. What doesn’t it tell us?

RK: It’s not going to tell us if a person who just got accepted into Harvard is actually going to be able to graduate [laughs]. It doesn’t provide useful information for behavioral or psychological traits. Also, as it relates to overall health, DNA plays some role, but it’s not one hundred percent. There are certain changes in the DNA that increase your risk for cancer, but what also plays a very significant role is exercise and lifestyle; what we consider the environment.

DNA is important for tracing ancestry because it’s like a record of the history of you as an individual, within your family, community, and within a particular region in the world.

EBONY: As far as tracing our ancestry is concerned, are there specific types of DNA that links us back to Africa?

RK: The one that’s really informative for African-Americans is mitochondrial DNA [mtDNA]. It’s passed on through women. Males receive it from their mothers, but they can’t pass it on to their kids. It represents the lineage of women in the family. We also look at the Y chromosome DNA, which is a history of the male lineage in the family. There are DNA patterns that are specific to Africans: For instance, there’s what we call a Y chromosome alu polymorphism [YAP] that is found just in West Africa, and is definitive for West African ancestry. But the most interesting thing is, when we look at most African-American men, upwards of thirty five percent of their Y chromosomes don’t go back to Africa; but to Europe!

EBONY: That’s because of slavery; African women mating with European men…

RK: That’s right. It’s really the behavior of slaveholders during slavery and afterwards … It’s what we call sex-biased gene flow. Of the genes from Europeans that came into the African-American population, the majority of them came from men.

EBONY: In the series, Professor Gates concluded that virtually all African-Americans are not one hundred percent African. Percentage wise, how do Black Americans break down, with regards to their African, European and Native American ancestries?

RK: We call that the admixture analysis. The bulk of African-Americans have about on average, twenty percent European ancestry. So that means that most African-Americans are about eighty percent West African. There are also a significant portion of individuals who, like Professor Gates, have significant European ancestry. I would say upwards of about fifteen percent of all African-Americans have greater than fifty percent European ancestry.

EBONY: Does DNA analysis also support Dr. Gates’ contention in the series that Black people have less Native American ancestry than they belief?

RK: Yes. It does support that. But there could be several reasons for that: We claim Native American ancestry before we claim European ancestry ... The other reason could be that some of the genetic markers that we have aren’t really that informative for Native American ancestry …The jury is still out. There is no strong consensus. We still maybe we’re missing a significant portion of the Native

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